Partial oxidation of methane to synthesis gas by a microwave plasma torch

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This study demonstrates a noncatalytic, low‐pressure, and room‐temperature process for methane partial oxidation into syngas by using a microwave plasma torch reactor. The experimental results showed that the elevation of the inlet O 2 /CH 4 molar ratio, pressure, and applied power led to the outlet H 2 /CO molar ratios decreased from 3.32 (at O 2 /CH 4 = 0.3, 13.3 kPa, and 160 W) to 0.81 (at O 2 /CH 4 = 1.5, 93.3 kPa, and 600 W). At O 2 /CH 4 = 0.5, the higher selectivity and yield of syngas, and a H 2 /CO molar ratio of about 2 could be obtained simultaneously. In addition, the maximum yield of syngas per unit mole of methane consumed could be achieved at a higher pressure, although a higher methane conversion was performed at a lower pressure. Based on these, this study suggests that the operating conditions of O 2 /CH 4 = 0.5 and near atmospheric pressure (93.3 kPa) would be the most appropriate combination for converting methane into syngas. Under the conditions, the selectivities of H 2 and CO reached 97.6 and 99.2%, respectively, accompanied with H 2 /CO = 1.97 at 600 W.